from tkinter import *
class PackMangerDemo:
    def __init__(self):
        window = Tk()
        window.title("packmanager demo 1")
        Label(window,text='blue',bg='blue').pack()
        Label(window,text='red',bg='red').pack(fill=BOTH,expand=1)
        Label(window,text='green',bg='green').pack(fill=BOTH)

        window.mainloop()

PackMangerDemo()
